Waver and Jeanne Np

look at their pages:

https://grandorder.gamepress.gg/servant/zhuge-liang-el-melloi-ii

https://grandorder.gamepress.gg/servant/jeanne-darc

Waver's NP at higher levels will increase the amount of defense debuff percentage per level (10%, 20%, 25%, 27.5%, 30% DEF down), whereas the chance of stun will increase with overcharge (50%, 57.5%, 65%, 72.5%, 80% Stun chance) [this is for NP Gauge at 100%, 200%, 300%, 400%, 500%; overcharge can go up to 400% or 500% if you have the NP gauge full at 300% and chain other NPs beforehand on the same turn] .

For Jeanne, the defense bonus granted by her NP increases per level (5%, 15%, 20%, 22.5%, 25% DEF Up), whereas overcharge increases the HP regeneration per turn (1000, 1500, 2000, 2500, 3000 HP per turn).